The work in this project is designed to understand the subcellular mechanisms involved in the renal transport of organic anions and cations. Previous work in this laboratory has demonstrated that a proteins(s) isolated from dog renal cortex can bind p-aminohippurate (PAH) and N1-methynicotinamide (NMN). By the addition of certain phospholipids we are able to form vesicles which transported both PAH and NMN. Further purification of this large glycoprotein has been difficult. In an effort to learn more about the properties of the protein(s) we propose to first determine the driving forces for the transport of both organic anions and cations. Using purutied luminal and antiluminal membranes isolated from dog renal cortex we examine the effects of Na ion and K ion on the Km of PAH and PAH influx and efflux. Secondly, to determine if the "carriers" in the two membranes are the same or different we will solubilize both membranes and determine their Km's. Once the properties of the "carrier" is established we will attempt to complete the purification of the protein by changing our solubilization procedure which may give a different protein pattern.